Pump



Nov. 8, 1960 L.. c. DERMoND 2,959,135

PUMP

Filed sept. 29, 195e IN VEN TOR. zwze/zcezfzzmd A Tram/Ey eral Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Sept. 29, 1958, Ser. No. 763,932 4 claims. (ci. 10s-iso) A The present invention relates to an improved type diaphragm actuated pump in which the movement of the diaphragm controls pump actuation. More specifically the present pump is of the type in which reciprocation of diaphragm means is adapted to draw liquid into and expel liquid from a chamber under the influence of a pneumatic force acting on the diaphragm means and which force is controlled by the position of such means.

While the subject pump is of general applicability, it is particularly effective when used as an automotive fuel pump on a vehicle having a convenient source of air pressure. In traditional pumps of the diaphragm type, it has been the practice to actuate the diaphragm through a cam and lever arrangement driven in accordance with engine speed. The present device represents an improvement over a mechanically driven type diaphragm pump in that all such mechanical actuating parts are eliminated and replaced with a simple air switch mechanism `greatly reducing both the cost and size of such pump. Y l

It is particularly an object of the present invention to provide a simple yet reliable air switch mechanism which will control the admission and exhaust of air into a diaphragm actuating chamber. The air switching mechanisms for the subject pump includes an overcenter type valve device which is actuated through an interconnection with the pump diaphragm so as to admit air pressure into the diaphragm chamber in one position and to exhaust such pressure therefrom in another position. This control of air pressure in combination with a diaphragm actuating spring combinesv to provide a simple but effective system for reciprocating the pump diaphragm.

Other objects and advantages of the present invention will be apparent from a perusal of the detailed description which follows.

In the drawings:

Figure 1 is a sectioned elevational view of the subject pump; and Y Figure 2 is a plan view of the pump showing parr ticularly the air switch mechanism.

Referring to Figure l, a diaphragm type pump is shown generally at and includes a rst or fuel casing -12 having inlet and outlet passages 14 and 16. A second or air casing is shown at 18 and is adapted to be mounted on fuel casing 12 through an intermediate casing 20. A rst or fuel' diaphragm 22 is peripherally .clamped between the' fuel casing 12 and intermediate `casing 20. A second or air diaphragm 24 is peripherally clamped between air casing 18 and casing 20.

In order to multiply the force available to pump fuel through casing 12, a differential area relationship -is established' between diaphragms 22 and 24. The differential area effect is achieved ybyforrn-ing the associated casings in such away that the area of fuel diaphragm 22 intermediate nitcd States Patent i() ICC is smaller than the area of air diaphragm 24. The desirability or need for this diiferential area effect is due to the fact that the air utilized for actuating diaphragm 24 is normally at a lower pressure value than is desired for pumping the fuel. Therefore, by the use of the differential area diaphragms, the fuel pumping pressure may be increased to its desired value. The chamber 26 defined by diaphragms 22 and 24 as well as casing 20 is vented to the atmosphere through a passage 28.

The fuel and air diaphragms are interconnected through a central stud 30 suitably secured to respective sets of reinforcing washers 32 and 34 whereby the diaphragms move in unison under the influence of the various actuating forces as will subsequently be considered.

The fuel casing 12 includes a chamber 36 which is communicated with the inlet and outlet passages 14 and 16 respectively through inlet and outlet valve devices 38 and 40. The inlet and outlet valve devices are of identical construction but are inverted with respect to each other so that when one is open the other will be closed and vice versa. While not shown in detail, valve devices 38 and 40 may include gravity or spring seating discs disposed in supporting cages such that the disc permits flow when moved in one direction and blocks such in the other direction. Inlet valve 38 is so arranged that upon the upward movement of diaphragm 22 fuel will be drawn into chamber 36. At the same time the outlet valve 40 will be closed. Downward movement of diaphragm 22 causes inlet valve 38 to close and outlet valve 40 to open permitting fuel from chamber 36 to be expelled through fuel outlet passage 16.

To facilitate easy :servicing of pump 10, the lower portion of fuel casing 12 is enclosed by a cover plate 42 removably secured to casing wall 44 through a stud member 46. Casing wall 44 separates the inlet and outlet fuel passages 14 and 16.

A spring S0 is seated upon Iwall 44 and engages reinforcing washer 32 of diaphragm 22 urging the diaphragm assemblies in an upwardly or pump charging direction.

To move the diaphragm in a fuel discharging direction against the force of spring 50, an air valve controlling mechanism indicated generally at 52 is provided for controlling the flow of air into and out of air chamber 54 defined by casing 18 and diaphragm 24.

The air valve mechanism is disposed in a raised portion 56 of casing 18 and enclosed by a removable cover plate S8. The chamber 60 within which the valve mechanism is disposed is in open communication with diaphragm chamber 54. An air inlet passage 62 is formed in casing 18 and terminates at its inner end in an upstanding boss portion 64 within chamber 60. A similar passage 66 and boss 68 are formed in casing 56 in vertically spaced relation to inlet yboss `64. 'Passage66- communicates the -chamber 60 to the atmosphere fto exhaustI any .air pressure within the chamber when such passage is open. It is to be noted that bosses 64 and 68 are laterally offset from each other. l

To control the ow of air through the inlet and exhaust passages 62 and 66, an overcenter type valve mechanism 70 is provided. As best seen in Figure 2,-valve 70 includes a generally flat or reed member 71 terminating at one end in a bifurcated portion 72. A spring member 74 is secured at onel end to valve member 70 intermediate the legs of the bifurcated portion 72. The spring is secured at its other end `to casing 56 to urge the valve axially against a stop member 76 formed on casing-56.

Valve member 70 also includes a pair of axially spaced closure elements 78 and-80 adapted to respectively `coact with inlet and outlet passage bosses 64j-and-68. It Ais `desirable to position valve-member70 vertically interthe pointofi-'pivotalcontact'between the bifurcated portion 72 of valve 70 and stop 76 is` on a line vertically equidistant between bosses 64 and 68 to achieve an overcenter or toggle type actuation of member 70. In other words, valve-member; 70 is moved downwardly causingsthe closuremember 78 to seat against the air inlet boss 64, member 70 will pass overcenter. A component of spring force is thereby created which urges member 70 in a clockwise direction to retain the valve in this position until such time as it is` moved overcenter in the opposite direction. In-.this latterinstance, the other closure member 80 willY seat against, boss` 68 closing the exhaust passage 66:`with.the=spring 74 again retaining the valve in `this position. dueto its. overcenter action` as noted'.

It isY apparent that-,itis-necessary-.only one of the passages 62 or- 66b'exopened at thel same time the other is closed. Therefore, Vvalve member 70 has only` two positions, eLg. a-.lowe'r positionin which closure member 78 blocks` the. air inlet-passage 62 under which circumstance exhaustpassage66 is-open and an upper position closing exhaust passaget 66 and opening inlet passage 62.

Valve member Wis-shifted between its two positions by an upstanding actuating arm 82 fixed at one end to diaphragm stud 30 and terminating at its other end in a horizontally extending bifurcated portion 84. The bifurcated portion of arm 82 includes the fingers 86 and 88 adapted to coactwith the free end of valve member 70.

With the parts in theposition shown, the air inlet boss 64 is covered by closure member 78 and the exhaust boss 68 is-uncovered whereby chambers 54 and 60 are maintained at substantially atmospheric pressure. Under this condition, spring 50 will move the diaphragm assembly 22-24-30 upwardly until such time as the lower iinger 88-of1 arm 82 engages valve member 70 moving-thesamefin any upwardly directionuntil spring 74 passes overcenter. At this timeY exhaustboss 68 will be closed and-air inlet boss 64'opened to admit air-into chamber 60. As the air pressure in chambers 66 and 54 builds up, diaphragm 24 will be moved downwardly causing diaphragm 22'to pump fuel from chamber 36. Downward movement'of the diaphragms continues until such time as upper finger 86 of arm 82 engages valve member 70 to again shift the member to its lower position to cut oi the supply of air and exhaust the pressure in chambers 54 and- 60 returning the diaphragms to their upper or charging positionsi able to a iirst position opening saidv inlet passage and closing said outlet passage, said valve member movable to a second position opening said outlet passage and closing said inlet passage, means associated with said irst and second diaphragm means for positioning said overcenter valve member in either said iirst or second positions, and resilient means nfor moving said iirst and second diaphragm means in a direction to position said overcenter valve member in said iirst position, said second set of inlet and outlet passages including a pair of spaced and oppositelyfacingv boss members, said second set of passages being formed in said boss members so that they open toward but are spaced from each other,

` and furthe; in, which said overcenter valve member in- Thus the actuation olf-fair valvev mechanism 52 is con- Y trolled by the movement o -thediaphragm assembly and the pumping cycle will: continue so long as the pressure in chamber 54 issuiiicient to' overcome the back pressureofthe fuel in outlet'passage 16. The stroke of pump 10 is determined by the space between fingers 86 andv 8Sl of arm 82, accordingly, the strokemay be varied by varying such distance.

Iclaim:

1'; A pump' comprising three-stacked casingmembers, first and-'second diaphragm means respectively peripherallyr''el'amper/1 Y between adjacent ofi' said three 'casing members, the first casing member including a iirst set of duid inlet and outletppassages, a uid chamber defined by said iirst diaphragmmeans and said first casing member, an inlet valvel disposed intermediate said chamber and-saidinlet passage,I an outlet valve disposed between said chamber and s-aidoutlet passage, movement of said diaphragm means in one direction being adapted to draw fluid'into saidnchamberA through said inlet valve, movement-d said4 diaphragm means" in the, opposite direction being adapted to expeljiuid from said chamber through saidmotutletl valve, a second uid chamber formed by saidy second `diaphragm means and the second `casing member, agsecond setofiiuid inlet and outlet passages formed in said" second casing member, an overcenter valve member mounted'in said second casing Aand movcludes a iiat plateelement being disposed intermediate said boss members and including closure portions adapted to respectively seat against and block dow through either the respective second inlet or the second outlet passages, said,valve: plateY element being pivotally supported on saidsecondgcasing member, spring means connected-aty one end to saidplate element and at the othen end to said casing in coaxial relation to the valve element, said `spring means urging said element into engagement with said second casing member, said diaphragm associated means being adapted to engage with and urge said valve element into either of said first or second positions, said spring means being adapted to retain said valve element inv either said rst or second position until such, time as the diaphragm associated means shifts the valve element to the other position.

2,. Arpump comprising first and second casings, a casing intermediate said first and second casings, a iirst flexible diaphragm means peripherallyclamped between said first and intermediate-casings, said iirst casing including iiuid inlet and outletl passages, `a chamber formed by said ii-rst diaphragmmeans and said first casing, a second diaphr-agm-.means-peripherally clamped between said second casing andsaid intermediate casing, an air chamber formed by said second diaphragm means and said second casing,A a: stud member interconnecting the diaphragms in spaced relation, an inlet valve disposed in said first casing intermediate said chamber and said inlet passage, an outlet valve formed in said iirst casing intermediate said chamber and said outlet passage, air inlet and outlet passages communicating with said air chamber, valve means mountedfin said second casing intermediate said air inlet and outlet passages,- said valve means being movable to a iirst-positionuncovering. said air inlet passage and covering saidai'r outlet passageand a second position covering said inlet passage and uncovering said outlet passage, an arm-fixed to said stud member and operatively connected to said valve means to shift the latter between its first'and second positions, said air inlet and outlet passagesincluding a pair ofspaced and oppositely facing boss members, said passages being formed in said boss members so that they open toward but are spaced from each other, said-valve means including a flat plate element being disposed intermediate said bossmembers and including closureportions adapted to respectively seat against and block ow through either the air inlet or a-ir outlet passage, said valve element being pivotally supported von said'se'cond casing member, spring means con'- nected at one end to said element and at the other end to said casing in coaxial relation to the valve element, said spring-means urging said plate element into engagement with` said casing, said armincluding a bifurcated end portion having first andseoond fingers adaptedv respectively toengage with and urge said` valve element into said first and second positions, said spring means being adapted to retain said valve element in either said first or second position until such time as the arm shifts the valve-element to-the otherl position.

3, A pump asset-forth in claim 2 in which the rst and second pgers of said armv are spaced from each other permitting relative movement between said valve element and said arm.

4. A pump as set forth in claim 2 in which the pivotal support of the valve element on the second casing member is disposed on a line equidistant between said bess members, said spring means being axially aligned with the valve element and exerting no rotating moment on said element when the latter is aligned with said equidistant line.

References Cited in the le of this patent UNITED STATES PATENTS Lane July 15, 1913 Curtis Nov. 24, 1914 Hueber et al Jan. 3, 1933 Hueber et al. Sept. 5, 1933 Laierty Feb. 7, 1939 

